🗊Презентация Java Core Introduction

Java Core Introduction IT Academy

Agenda Introduction to Java Platform. Java SDK Environment and Development Tools for Java applications Eclipse IDE Tips & Tricks The Entry Point into the Program Java Packages. Introduction My first program

Introduction to Java Platform James Gosling, Mike Sheridan, and Patrick Naughton initiated the Java language project in June 1991. The language was initially called Oak after an oak tree. Now, Java it is the name of a platform and language. Java applications are typically compiled to bytecode (class file) that can run on any Java Virtual Machine (JVM) regardless of computer architecture. The original and reference implementation Java compilers, virtual machines, and class libraries were developed by Sun from 1995 (May 23, 1995, Java 1.0). With the advent of Java 2 (JDK 1.2, released initially as J2SE 1.2 in December 1998–1999), new versions had multiple configurations built for different types of platforms.

Introduction to Java Platform Sun distinguishes between its Software Development Kit (SDK) and Runtime Environment (JRE) (a subset of the SDK); the primary distinction involves the JRE's lack of the compiler, utility programs, and header files. Sun also distributes a superset of the JRE called the Java Development Kit (commonly known as the JDK), which includes development tools such as the Java compiler, Javadoc, Jar, and debugger. The JDK forms an extended subset of a SDK. In the descriptions which accompany its recent releases for Java SE, EE, and ME, Sun acknowledges that under its terminology, the JDK forms the subset of the SDK which has the responsibility for the writing and running of Java programs.

Introduction to Java Platform Specification Java 2 (JDK 1.2) – 1998/1999 (strictfp; collection support; Swing; GUI; drag-and-drop; CORBA; Unicode; JIT compiler). Sun renamed new J2 versions as Java EE, Java ME, and Java SE. Specification Java 5 (JDK 1.5) – September 2004 (enum type is class; generics mechanism, templates analog of C++; foreach; Autoboxing/Unboxing: for example, scalar and wrapper type int – Integer; Javadoc; etc.)

Platform Components JDK = JRE + Development/debugging tools JRE = JVM + Java Packages Classes(like util, math, lang, awt,swing etc)+runtime libraries. JVM = Java Virtual Machine

Detailed Diagram of Java Components

Java JDK http://www.oracle.com/technetwork/java/javase/downloads/index.html

Install Java In System Variables enter the variable name as JAVA_HOME and the variable value as the installation path for the Java Development Kit

Install Java java -version

Java JDK. Entry Point public class Example { public static void main(String[ ] args) { System.out.println("My first program"); } } To display information on the screen it’s used System.out.println("Text1"); System.out.println("Text 1 " + "Text 2");

Java JDK

Java JDK For Compile: javac Example.java Output file: Example.class For Running: java Example Exception in thread "main“ java.lang.NoClassDefFoundError: Example java -cp "Example.class;" Example For Creating Java archive: jar cvfm Example.jar Manifest.mf Example.class java -jar Example.jar

Program Entry Point public class ShowArgs { public static void main(String[ ] args) { for (int i=0; i<args.length; i++) { System.out.println("Arg " + i + " is " + args[i]); } } } or public class ShowArgs2 { public static void main(String[ ] args) { for (String arg: args) { System.out.println("Command line arg: " + arg); } } }

Some types of data

Online Java compiler http://www.tutorialspoint.com/compile_java_online.php https://ideone.com/ https://www.compilejava.net/ http://www.browxy.com/ https://www.jdoodle.com/online-java-compiler

Environment, Development Tools NetBeans began in 1996 as Xelfi (word play on Delphi). In 1997 Roman Staněk (Charles University in Prague) formed a company around the project and produced commercial versions of the NetBeans IDE until it was bought by Sun Microsystems in 1999. Sun open-sourced the NetBeans IDE IntelliJ IDEA is a commercial Java IDE by JetBrains. It is often simply referred to as 'IDEA' or 'IntelliJ'. A 30-day fully functional trial of the IntelliJ IDEA commercial edition for various platforms can be freely downloaded. Also available is an open source Community Edition. The first version of IntelliJ IDEA appeared in January 2001. Community Edition is open-source

Environment, Development Tools JCreator is a Java IDE created by Xinox Software. Its interface is similar to that of Microsoft's Visual Studio. JCreator has two editions: Lite Edition (LE) is freeware and Pro Edition (Pro, 30-days trial). JCreator is only available on the Windows Operating System. Eclipse is a multi-language software development environment comprising an integrated development environment (IDE) and an extensible plug-in system. It is written primarily in Java and can be used to develop applications in Java and, by means of various plug-ins, other languages including C, C++, COBOL, Python, Perl, PHP, Scala, Scheme and Ruby (including Ruby on Rails framework) http://www.eclipse.org/downloads/

Eclipse

Eclipse

Packages Java package is a mechanism for organizing Java classes into namespaces. Programmers also typically use packages to organize classes belonging to the same category or providing similar functionality. A package provides a unique namespace for the types it contains. Classes in the same package can access each other's package-access members. package java.awt.event;

Packages imports all classes from the package import java.awt.event.*; imports only the ActionEvent class from the package import java.awt.event.ActionEvent; . . . ActionEvent myEvent = new ActionEvent(); Classes can also be used directly without an import declaration java.awt.event.ActionEvent myEvent = new java.awt.event.ActionEvent();

Packages. Java java.lang – basic language functionality and fundamental types java.util – collection data structure classes java.io – file operations java.math – multiprecision arithmetics java.awt – basic hierarchy of packages for native GUI components javax.swing – hierarchy of packages for platform-independent rich GUI components The java.lang.* package is available without the use of an import statement.

Packages Package names and type names usually differ. package Vector; public class Mosquito { int capacity; } //- - - - - - - - - - - - - - - - - - - - package strange.example; import java.util.Vector; import Vector.Mosquito; class Test { public static void main(String[ ] args) { System.out.println(new Vector().getClass()); System.out.println(new Mosquito().getClass()); } }

Input data To input value during the run time you can use BufferedReader br = new BufferedReader( new InputStreamReader(System.in)); String text = br.readLine(); int age = Integer.parseInt(br.readLine()); double t = Double.parseDouble(br.readLine()); Or Scanner sc = new Scanner(System.in); name = sc.nextLine();

My first program package com.edu; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; public class Main { public static void main(String[] args) throws IOException { BufferedReader br = new BufferedReader( new InputStreamReader(System.in)); System.out.println("Hello. What is your name?"); String name = br.readLine(); System.out.println("How old are you?"); int age = Integer.parseInt(br.readLine()); System.out.println("Hello " + name); System.out.println("You are " + age); } }

Tasks Create Console Application project in Java. In method main() write code for solving next tasks: Define integer variables a and b. Read values a and b from Console and calculate: a + b, a - b, a * b, a / b. Output obtained results. Output question “How are you?“. Define string variable answer. Read the value answer and output: “You are (answer)".

HomeWork (online course) Please register on UDEMY course "Java Tutorial for Complete Beginners": https://www.udemy.com/java-tutorial/ Complete lessons 1-7:

HomeWork Install JDK and Eclipse. Create Java project. Create console application. In method main() write code for solving next tasks: Flower bed is shaped like a circle. Calculate the perimeter and area by entering the radius. Output obtained results. Define string variable name and integer value age. Output question "What is your name?" Read the value name and output next question: “Where are you live, (name)?". Read address and write whole information. Phone calls from three different countries are с1, с2 and с3 standard units per minute. Talks continued t1, t2 and t3 minutes. How much computer will count for each call separately and all talk together? Input all source data from console, make calculations and output to the screen.

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